Peel and chop the potatoes to roughly 1 inch cubes. Transfer potatoes to the slow cooker, add garlic, 1 cup broth, and 1/2 cup cream.
Cook until potatoes are tender, about 4 to 5 hours on high.
Warm the remaining cream to at least room temperature and melt the butter. Mash the potatoes, then add the melted butter and stir. Add the cream slowly, about 1/2 cup at a time, until the proportions are the way you like. Season with salt and pepper, to taste.
Keep warm until ready to serve. Top with your favorites, like chives, cheese, or a fresh pa1 of butter.